Ignition distributor for internal combustion engines



y 1, 1959 .R. SALOMON 3,452,728

IGNITION DISTRIBUTOR FOR INTERNAL COMBUSTION ENGINES Filed 0ct. 9, 1967 Sheet of 3 M I M [M MANIFOLD VACUUM l V kif I JJE ADVANCE RPM. CURVE I e r (Dc-\f- A (CRANKING SPEED WM x' ADVANCE m DEGREES I m ORIGINAL INVENTOR ADVANCE SETTING ROGER SALOMON BY M 4 AMI-4 ATTORNEYS R. SALOMON 3,452,728

IGNITION DISTRIBUTOR FOR INTERNAL COMBUSTION ENGINES July 1, 1969 Sheet Filed Oct. 9, 1967 INVENIDR ROGER SALOMON ATTORN R. SALOMON IGNITION DISTRIBUTOR FOR INTERNAL COMBUSTION ENGINES Filed Oct. 9, 1967 Sheet FIGS INVENTOR ROGER SALOMON WZ Z ATTORNEYS.

United States Patent 3,452,728 IGNITION DISTRIBUTOR FOR INTERNAL COMBUSTION ENGINES Roger Salomon, Virofiay, France, assignor to Ducellier et Cie, Paris, France, a French company Filed Oct. 9, 1967, Ser. No. 673,890 Claims priority, application France, Oct. 15, 1966, 79 473 Int. (:1. im /12 U.S. Cl. 123-117 5 Claims ABSTRACT OF THE DISCLOSURE Background of the invention The known distributors of this type are designed in such manner that the two adjustments operate independently from one another. As already known the centrifugal adjustment causes a displacement of the breaker cam relatively to the breaker arm in relation to engine speed, while the vacuum adjustment modifies, in relation to the vacuum existing in the inlet manifold, the angular position of the breaker plate on which the breaker arm and its fixed contact are secured, thus changing the position of said plate relatively to the breaker cam. Normally, the vacuum existing in the inlet manifold is applied to a diaphragm which is connected by a rod to the breaker plate and causes it to rotate in the direction of ignition advance as manifold vacuum increases, i.e. the pressure becomes more negative.

Heavy trafiic in cities results in very serious pollution of the surrounding air. In order to bring a remedy to this pollution it is necessary to decrease the production of gases resulting from the combustion of the mixture supplied to the engines. It is therefore necessary to adjust the carburators in order to produce a leaner mixture by decreasing the gasoline percentage of said mixture. This results in the necessity to produce at idle speed a delay or retardation in ignition timing relatively to the original advance setting which is necessary to allow the engine properly to start.

The ignition timing curve must therefore produce some predetermined ignition timing which allows easy starting which is then relatively retarded as soon as the engine starts and is idling, whereafter at speeds greated than idling speed the normal centrifugal-vacuum advance curve is followed for proper performance and power while the engine is under load.

To obtain such an ignition curve, varied solutions have been offered such as the one consisting of rotating the distributor housing a certain amount at the start and until idle speed so that the breaker arm revolves in the direction corresponding to a delay. This solution is complex and expensive.

Another solution proposes to supply a suction on both sides of the diaphragm of a vacuum chamber controlling the advance mechanism so that the ratio of the applied suctions causes a given delay at idle speed. This solution is extremely delicate because the two chambers on either side of the diaphragm must be absolutely air-tight and the movable parts actuated by the diaphragm must therefore be provided with seals which create additional friction detrimental to the obtention of an accurate ignition curve.

Still another solution consists of rotating the breaker plate in the direction of ignition advance by means of an advance adjustment connected to said plate and controlled by means of a vacuum chamber subjected to the suction prevailing in the manifold and provided with a first spring opposing the rotation of the breaker plate to allow several advance positions in relation to suction variations while an ignition delay mechanism also connected to the breaker plate and controlled by a second vacuum chamber is connected to cause the rotation of said plate in the direction of ignition delay.

This delay mechanism is connected to the breaker plate by means of a slot containing said mechanism, the ends of the slot respectively corresponding to the greatest delay and to the greatest advance. So that, at rest, that is to say in the position corresponding to the original setting of the ignition advance the delay mechanism assumes a position of equilibrium between the two stops formed by the ends of the slot. This equilibrium position is unstable because of vibrations and very difiicult to adjust.

Summary of invention The present invention overcomes the foregoing disadvantages and relates to an ignition distributor incorporating a centrifugal adjustment changing the position of the breaker cam relatively to the breaker arm in relation to the speed, an advance adjustment controlled by a vacuum chamber operated by the vacuum existing in the inlet manifold and connected to the advance arm supporting the breaker arm to cause the rotation of the latter in the direction of ignition advance and delay mechanism controlled by a second vacuum chamber subjected to another vacuum source, independent from the first vacuum source, and arranged in such manner as to cause the rotation of said breaker arm in the direction corresponding to an ignition delay, characterized in that the delay mechanism is connected to a movable stop against which the advance adjustment is applied by means of a spring. Said stop keeps said mechanism while at rest in the position of original advance setting and retracts itself when the engine is idling thus causing under the biaising effect of the spring a displacement of the breaker arm in the direction of ignition delay.

Brief description of drawings FIG. 1 is a schematic representation of the operation of the distributor according to the new advance adjustment which is intended.

FIG. 2 is a graph representing the advance curve obtained with the distributor according to the invention.

FIG. 3 is a longitudinal sectional view of a complete distributor according to the invention.

FIG. 4 is a plan view of the breaker housing with the distributor cover removed, and

FIG. 5 is a tranverse sectional view taken along line VV of FIG. 3.

Detailed description of the invention The distributor shown in FIGURES 3, 4 and 5 comprises a housing 1 through which passes a control shaft 2 which is rotatably driven by the engine through the medium of a gear 3 or any other driving arrangement. Onto shaft 2 is affixed a disc 4 which carries the centrifugal advance components generally designated by numeral 5. The usual rotor 8 is affixed for rotation with the cam 6 and its contact blade 9 distributes the high tension voltage to the respective terminals 10 to which the spark plug leads are connected in the usual fashion.

Breaker 7 is pivotally mounted about a pin 11 fixed on an advance lever 12 which is pivoted about a pin 13 ati tached to breaker support plate 14 in turn secured to housing 1. Spring 15 constantly urges finger 16 of breaker 7 against cam 6. At the end of breaker 7 a point 17 is secured for cooperating with a fixed point 18.

These two contact points are electrically connected to the primary winding of the ignition coil.

Vacuum chamber 20 is secured to the outside of housing 1 and controls the ignition advance. It comprises a chamber 19 connected by means of tubing 21 to the suction side of the engine and a resilient membrane 22 at the center of which is secured a rod 23 which by means of spring 24 is urged in a direction opposite the action of the vacuum on membrane 22. The displacement caused by the vacuum is transmitted through rod 23 to advance lever 12 which pivots about pin 13 while carrying breaker 7 mounted about pin 11 integral with advance lever 12.

The pin 25 around which lever 12 and rod 23 are secured is provided at its lower end, below lever 12, with a roller 26 which is mounted off center on pin 25. Roller 26 is received in an aperture 27 provided in breaker support plate 14, the distance between the ends 27a and 27b of which determining the total amplitude of the advance and delay adjustment since it controls the angular displacement of lever 12 and of breaker 7 between the extreme positions of finger 16 in contact with cam 6. By rotating roller 26 it is possible to accurately adjust the extreme positions of finger 16 within the limits of the predetermined amplitude (FIGURES 3 and 4).

Furthermore an eccentric 28, provided with teeth at its periphery, is rotatably mounted around pin 25 and, depending upon its angular position, is capable of changing the position of the last turn of spring 24 relatively to pin 25, which spring opposes the action of the vacuum existing in the inlet manifold and engages eccentric 28 by means of cup 29. Therefore by pivoting eccentric 28 around pin 25 it is possible to accurately adjust the original compression of spring 24 (FIGURE 4).

According to the invention a second vacuum chamber 30 identical to chamber 20 is secured approximately opposite the first on the outside of the housing and controls the ignition delay mechanism which comprises a rod 31 urged by a spring 32 in a direction opposite the displacement resulting from the action of a vacuum on the membrane or diaphragm of chamber 30. The action caused by the vacuum is conveyed by means of rod 31 to a movable stop 33 integral with a sliding member 33a which stop is also in engagement with roller 26 mounted on lever 12 and urged by spring 24.

The pin 34 connecting rod 31 to sliding member 33a of movable stop 33 is provided at its lower end, below member 33a, with a washer 35 mounted off center on pin 34. Washer 35 is located in an elongated aperture 36 provided in a support 37 carrying slide member 33a and secured to the inside of housing 1. The edge 38 of aperture 36 against which bears washer 35 while at rest determines the starting point of the ignition advance curve and limits the action of spring 32. By rotating pin 34 it is possible to adjust accurately the position of the movable stop at the origin of the advance curve.

An eccentric 39, identical to eccentric 28, in engage ment with the spring 32 by means of cup 40, can modify the position of the last turn of spring 32 relatively to pin 34 to adjust the action of said spring in opposition to the action of the vacuum. Therefore by rotating eccentric 39 it is possible to accurately adjust the original compression of spring 32, said compression must be greater than the compression of spring 24 so that the movable stop 33, in abutment by means of Washer 35 engaging edge 36, be susceptible to keep while at rest the advance mechanism in the starting position A of the ignition advance curve (FIGURES 1, 2, and 5).

Two pins 41 and 42 secured to support 37 and received in a slot provided in sliding member 33a ensure longitudinal guidance of said sliding member while the two enlargements'44 and 45 appearing at the ends of pins 41 and 42 keep it from moving transversely (FIGURE 5 The distributor is schematically represented in FIG- URE 1 in the rest postion at the beginning of the ignition advance curve. The starting point of the advance curve is indicated at A in FIGURE 2 located in line X designating the original advance setting.

In this figure the curve is plotted in function of the number of r.p.m. of the distributor shaft and of the advance in degrees.

In the rest position (FIGURE 1) roller 26 urged by spring 24 is in abutment with movable stop 33 the displacement of which is in turn prevented by contact of washer 35 with edge 38 of aperture 36 spring urged by spring 32.

Spring 32, stronger than spring 23, keeps roller 26 still, together with advance lever 12 carrying breaker 7.

When the engine is started the distributor shaft revolves (the direction of rotation of the distributor shaft is indicated by arrow F on FIGURE 1), vacuum existing in the inlet manifold is first applied to vacuum chamber 30 bringing in rod 31 and stop 33 in the direc tion of arrow F until said stop moves to position 33a indicated in dotted lines. Roller 26 secured to lever 12 is forced by spring 24 to follow the displacement of moveable stop 33 until it comes in contact at 27a with the end of the slotted aperture 27 which determines the entrance position of the ignition delay while the engine is idling.

During the displacement of stop 33, advance lever 12 which pivots about pin 13 is rotated in the direction of arrow F bringing with it breaker 7 which results in an ignition delay shown on FIGURE 2 by straight line AB or AC corresponding to the adjustment range of idling speed.

As soon as the engine accelerates, the vacuum supply to chamber 30 is interrupted and applied instead to chamber 20 resulting in the displacement of roller 26 in the direction of arrow F and the rotation of advance lever 12 in the direction of arrow F Breaker 7 therefore moves in a direction corresponding to an increase of the advance until the original advance setting is reached (line BD or CD of FIGURE 2), from then on the standard ignition advance curve is traced which results from the action of the centrifugal adjustments and of vacuum ad- Vance adjustment controlled by vacuum chamber 20.

It is possible not to interrupt the supply of vacuum to chamber 30 when the same is directed to chamber 20. If such is the case the ignition advance curve begins at point B or C instead of point D.

Control of manifold vacuum to the two chambers 20 and 30 may be established in response to the carburetor throttle valve position. For example, a microswitch S may be actuated by the positioning of the throttle shaft arm against the idle stop to control a valve V which disconnects the line M leading to the chamber 20' from manifold vacuum while simultaneously connecting the line N leading to the chamber 30 to manifold vacuum. Thus, at any time the engine is idling the throttle shaft actuating arm is against the idle stop, the ignition is relatively retarded (point B or C in FIG. 2 dependent up the idling speed to which the idle stop is adjusted). At any time that the throttle valve arm is moved away from the idle stop, the microswitch causes the valve to connect the chamber 20 to manifold vacuum and disconnect the chamber 30 therefrom. In this case, the ignition curve will undergo an immediate advance (line BD or CD, in FIG. 2) whereafter the normal advance curve is followed. Alternatively, the microswitch S may operate the valve V only to control the line M between chamber 20 and manifold vacuum, line N leading to chamber 30 remaining always connected to manifold vacuum In this case, the normal advance curve will commence at point B or C in FIG. 2.

It will be understood that the range B-C represents an idling adjustment which has been made after the engine is started and that there will be some slight ignition advance along this line due to the action of the centrifugal advance mechanism. In other words, in the case where chamber 30 is disconnected when chamber 20 is connected to manifold vacuum, if the carburetor had been left to retain the idle speed corresponding to point B, the advance curve would have proceeded from B directly to D as the throttle valve arm is moved away from its idle stop. Or the adjusted idle speed could be anywhere within range B-C in which case the line AB would be replaced by a line directly connecting A to such point in range B-C.

In any event, the chamber 20 must be disconnected from manifold vacuum while the engine is idling and the spring 24 must be eifective to follow the stop 33 to the position of maximum retardation of the breaker arm 7.

It is quite obvious that the specific realization which has been described above in reference to the attached drawings has been given for illustration purpose only and is not intended to limit the scope of the invention What is claimed is:

1. In an ignition distributor for internal combustion engines, said distributor having a centrifugal advance mechanism and a manifold vacuum advance mechanism, the latter of which is operative to advance the ignition timing as the manifold vacuum increases, the improvement comprising,

movable stop means normally establishing a maximum retarded position of said vacuum advance mechanism when the engine is not running,

means disabling said vacuum advance mechanism when the engine is idling,

and manifold vacuum means for moving said stop means in the direction of ignition retardation when the engine is idling.

2. In the distributor according to claim 1 including valve means for simultaneously disabling said manifold vacuum means and enabling said vacuum advance mechanism as the engine is caused to increase its speed beyond idling.

3. In the distributor according to claim 1 wherein said manifold vacuum means is continuously connected to manifold vacuum and including valve means for enabling said vacuum advance mechanism as the engine is caused to increase its speed beyond idling.

4. In the distributor according to claim 3 wherein said movable stop means is in the form of a slide member having a bent tab forming the stop, a pair of pins received in an aperture in said slide member and attached to the distributor, and a cap on said pins for containing the slide member transversely.

5. In the distributor according to claim 1 wherein said vacuum advance means includes a rod attached to a flexible diaphragm and to the breaker arm of the distributor, said breaker arm engaging said movable stop means, a first spring urging said rod to engage said movable stop means, and said movable stop means including a second spring stronger than and opposing said first spring.

References Cited UNITED STATES PATENTS 2,557,527 6/1951 Colvin et al. 123117.1 2,596,830 5/1952 Udale 123117.1 2,731,523 1/1956 Downing 123117.1 2,773,141 12/1956 Baker 123117.1 2,809,619 10/1957 Norris 123-1 17.1 2,809,620 10/1957 Boylan 123-117.1 3,027,884 4/1962 Bale et al. 123117.1 3,062,929 11/1962 Larges et al. 123-117.1 3,252,450 5/1966 Dietrich et al. 123117.1 3,272,191 9/1966 Walker 123117.1 3,306,272 2/ 1967 Bevacqua 123117.1

FOREIGN PATENTS 1,104,717 6/1955 France.

WENDELL E. BURNS, Primary Examiner. 

